test: refactor test framework to use a rootfs skeleton

Instead of having to create files, and copying them in place for each
test, we move all static test files to a skeleton rootfs.  This makes
it a lot easier to get an overview of how things and how they work.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

test/skel/sbin/chrootsetup.sh

@@ -0,0 +1,52 @@
+#!/bin/sh
+# Setup the things (mount /proc, /tmp, etc.) that needs to be set up from
+# within the namespace/chroot and then start PID 1.
+#
+# Copyright (c) 2021  Jacques de Laval <jacques@de-laval.se>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+set -eu
+export PATH=$PATH:/usr/bin:/usr/sbin
+
+# It would have been nice to mount /dev as devtmpfs, but unfortunately
+# that's not possible if you're not privileged. For now tmpfs will
+# have to do.
+mount -n -t tmpfs none /dev
+# Silence BusyBox init
+touch /dev/null
+
+mount -t proc none /proc
+mount -t sysfs none /sys
+
+if [ "$(ls -A /tmp)" ]; then
+	mkdir -p /tmp.shadow
+	mount --bind /tmp /tmp.shadow
+	mount -t tmpfs none /tmp
+	cp -a /tmp.shadow/* /tmp/
+else
+	mount -t tmpfs none /tmp
+fi
+
+mkdir -p "$FINIT_RCSD"
+
+tty=/dev/$(cat /sys/class/tty/console/active)
+mkfifo "$tty"
+
+exec "$@"

test/skel/sbin/service.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+cleanup()
+{
+	echo "Got signal, stopping ..."
+	rm -f /run/service.pid
+	exit 0
+}
+
+# Hook SIGUSR1 and dump trace to file system
+# shellcheck disable=SC2172
+trap 'echo USR1 > /tmp/usr1.log' USR1
+trap cleanup INT
+trap cleanup TERM
+trap cleanup QUIT
+trap cleanup EXIT
+
+echo $$ > /run/service.pid
+
+# sleep may exit on known signal, so
+# we cannot use 'set -e'
+while true; do
+	sleep 1
+done